This invention generally relates to a method for processing data in a data processing system, e.g., in a programmable controller for automation of an industrial installation. More particularly, the invention relates to a method for processing data in a data processing system within a machine, a manufacturing plant, a process engineering plant or a power plant. The invention also relates to an associated data processing system.
Data processing systems are used in a variety of ways within the context of industrial automation processes. For example, they are used where complex industrial installations combine a plurality of data processing units into complex computer networks and data networks via at least one data transmission unit. For operation and/or observation of the data processing units controlling the installation, usually so-called operator stations or operation and observation units are provided. For controlling and/or regulating the industrial installation, each data processing unit includes data processing programs.
A data processing program usually includes, for example, an operating program, a main program, or a main routine, in which a number of control commands and/or data processing commands for the industrial installation are processed sequentially. Such a data processing program for an automated industrial installation having a user-specific design, such as a manufacturing plant, a machine tool or a measurement system, is also referred to as user software. From this main program, so-called subroutines or function modules are retrieved as needed, e.g., cyclically or by an event-triggered system. These function modules are modules which take over certain self-contained control functions and/or regulating functions. The main program accesses individual function modules which are stored, for example, in separate executable data files. In addition, the main program, subroutines or function modules access data that is provided as needed, e.g., via data memory modules (or simply data modules).
The data processing program usually runs in the data processing units, e.g., in a central control unit and in the centralized onsite controls of the industrial installation, and it controls, among other things, the exchange of data between the central control unit and components of the industrial installation. Switching commands or manipulated variables are transmitted by the data processing program to the components on the one hand, while on the other hand measured data or characteristic process parameters and/or control parameters are read from the components. Depending on the type and design of the industrial installation, one data processing unit may also access the data processing program, in particular a function module and/or data module, of another data processing unit.
Due to changes in the process sequence, it may become necessary to adapt, and thus make changes to, the function modules or data modules of the data processing programs of individual data processing units or a plurality of data processing units and/or operator and observation units during the manufacture of such user-specific data processing programs or during ongoing operation of the installation. These program-specific changes may result in so-called specification errors, which may under some circumstances result in failure of individual data processing units or even the entire data processing system. Such a specification error may also be relevant for plant safety on the whole and may thus lead to failure of the entire production installation.
A specification error occurs, for example, when an object, i.e., a function module or a data module or a data processing unit, is altered, i.e., redesigned, but this change in the object does not take place simultaneously within all the data processing units in question. In other words, a change in a function module or a data module leads to changes in the data processing program of the data processing unit affected as well as changes in the data processing program of other data processing units that are exchanging data with the respective data processing unit. Since updating all relevant data processing units does not occur simultaneously, incompatibilities may occur among them. These incompatibilities may result in, for example, an access error in the processing of the data processing programs that have not yet been altered. Such an access error will cause a failure in this data processing unit or a failure of or a disturbance in the production plant controlled by the data processing unit.